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Various boiler manufacturers including Ideal Heating use the F1 fault code, including:
Whilst the wording changes depending on the manufacturer, the fault is consistent across all brands; your system is suffering from low water pressure.
The only difference comes for those boilers mentioning circulation errors and dry-fire protection faults (Glow-Worm and Baxi) as the list of potential errors is much bigger.
Your display flashing the F1 boiler fault code suggests low water pressure (which we’ll explain in detail below). Typically, this means there is some kind of leak in your central heating system.
However, if your pressure gauge is showing 1-1.5 bar when cold and 1.3-2 bar when hot, it’s likely not a water pressure issue.
Instead, there are two other culprits worth checking out.
The first, is the water pressure sensor. If your boiler pressure is correct but your unit is locking out and displaying the F1 fault code, it’s likely the water pressure sensor is faulty and needs replacing.
On very rare occasions, the issue lies with the Printed Circuit Board (PCB). The PCB is the brains of the boiler, much like an ECU is on a car. If there’s a fault with your PCB, it’s going to need to be replaced.
The F1 fault code is shown on all of Ideal's top boilers including:
As we mentioned above, this guide is also relevant to the majority of Worcester, Vaillant, Glow-Worm, Baxi, Potterton and Main boilers.
Below are the top causes of the F1 fault code and how to fix them.
Basic plumbing leaks are the most common culprit causing the F1 boiler fault code to display on modern boilers. The quicker your boiler pressure is dropping, the bigger the leak.
You can visually inspect: radiator valves, radiators and pipework to see if you can see even the slightest leak. Alongside this, check skirting boards, ceilings and floors for signs of damp.
Less common leaks come from boiler pumps. Do a visual check underneath your boiler. Are there any leaks?
A leaking pump could be dripping directly onto electrical components and be detrimental to your boiler’s lifespan. As this is a boiler component, this should only be inspected / repaired by a Gas Safe engineer.
Once fixed, they’ll be able to top up water pressure, reset your boiler and clear the F1 error code.
It’s rare that water pressure sensors and PCBs fail, but it certainly happens.
If your Gas Safe engineer is able to pinpoint the issue to the water pressure sensor, that’s likely to cost £150-£300 to fix. Prices vary depending on the cost of parts, as well as labour costs in your area.
The PCB is a different story. Expect to pay £400-£500+ including diagnostic, parts and labour for installation.
For boilers requiring a PCB replacement, it makes much more sense to invest in a new boiler with a long warranty than repair one that’s old, inefficient and deteriorating.
You can get quotes on a new boiler here to compare repair vs replacement cost.
If there are no obvious leaks, it’s worth checking the Pressure Release Valve (PRV) and the expansion vessel.
A PRV is a component there to protect your boiler. If there’s a sudden spike of pressure (usually to 3 bar) it will release water to drop the pressure in your system.
Once the system settles, it’s likely the pressure is then too low. And, if the PRV is stuck open, your central heating system will continue to lose pressure and show the F1 boiler error code.
Likewise, the expansion vessel could be the culprit. This is the component that absorbs water as your system pressure increases. A faulty vessel will mean pressure spikes unexpectedly and the PRV (even when working correctly) will release water, and therefore pressure.
Like many boiler fixes, by the time you’ve paid for diagnostic and repair, fixing the expansion vessel or PRV could be £250+, or £500+ if your boiler needs both replaced.
Any work on a gas boiler should be completed by a Gas Safe engineer. Do not attempt a DIY fix.
There are a few instances where it’s common to bleed radiators. Sometimes, this is simple maintenance, but it’s also common after system upgrades.
If you or a heating engineer bleeds one or all of your radiators, this removes air trapped in the system, helping your system to run more efficiently. The more air you bleed from a system the better, but, this will result in a substantial pressure loss.
If this loss drops your system pressure much below 1 bar, you’ll see the Ideal F1 boiler fault code displayed. Your unit will lock out until the issue is fixed and the boiler is reset.
Occasions where you might bleed air from your radiators include:
Of all the fixes, this is the easiest. Most boilers have an isolation valve and a built-in filling loop. Simply open the isolation valve and top up your boiler to the pressure recommended by your manufacturer.
Once topped up, resetting your boiler should clear the F1 error code on your Ideal boiler’s display.
Warning: Pressures will be approximately 0.5 bar higher when your system is completely up to temperature versus when they are cold.
Determine whether your manufacturer’s recommended pressures relate to pressure when hot or cold.
The F1 error code on Ideal, Worcester, Vaillant, Glow-Worm, Baxi, Potterton and Main boilers relates to low boiler pressure. It’s likely you have a leak in your heating system or boiler.
It’s unlikely a boiler showing the F1 error code is dangerous.
However, it likely points to a leak and water leaking could cause damage to your property.
To reduce boiler pressure you’ll need to either: bleed air from radiators, drain water from the bleed valve on a radiator or, use the drain tap on a radiator to remove water from your heating system.
Most modern Ideal boilers have a dial with 4 settings: boiler off, hot water on, hot water and heating on, and restart.
Simply turn the dial to “restart”, then put it back into the hot water and heating on position.
Generally speaking, fixing the F1 boiler fault code is fairly easy and inexpensive (sometimes free), so you won’t need a new boiler.
However, if your Gas Safe engineer thinks you need a new pressure sensor, PRV, expansion vessel or PCB, these repairs can cost £100s. It makes little sense investing big money into an old and unreliable boiler, so a replacement might be the most cost effective option long-term.
And that’s it for our guide to the F1 fault code on Ideal boilers.
If you’re looking at an expensive repair on an old boiler, it’s worth comparing repair versus replacement costs using our clickable boiler quote form here.
Try our free quote tool. You'll have your personalised quote in under a minute.
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